Return false cancels the default action, which is to link
to "whatever.htm". By cancelling the default action, the image above becomes
exclusively a button that prints a document, which is what we want in this case. (Note:
there is another similar way to achieve the same thing, which is to create a false (non
existence) anchor link, and taking out the return false part.)

2nd method: Using a "JavaScript url" in an
image link:

Another way to accomplish the exact same task as above is to use a
"JavaScript url". A JavaScript url is a special kind of url that executes a
command, instead of loading the specified url. Lets see an example of such before
explaining what exactly it is:

<a href="javascript:window.print()"><img src="print.gif"></a>

The part in red is a JavaScript method, but look at where
it is inserted-in place of the target link! The syntax for all JavaScript urls are the
same:

javascript:script codes here

Any JavaScript code can be inserted inside to
carry out an action when a link is clicked, thus the name, JavaScript url! For example,
the below will pop up an alert box when the link is clicked: